442 INNERVATION. [CHAP. XV. 



ing : in those of taste, the epithelium is permeated by the special 

 excitant of the nerves ; while the intestinal villi are still more elabo- 

 rately and exclusively organized for absorption. Another class of 

 papillae might be here spoken of in conjunction with those of taste, 

 as will be seen at a future page. 



On the precise Seat of Taste. Authors differ considerably on this 

 subject : some limit it to the hinder part of the tongue, about the 

 root and sides; some extend it more or less over the whole dorsal 

 aspect and to the tip ; others describe it as existing also on the soft 

 palate ; while Majendie is of opinion that the pharynx, gums, and 

 teeth are likewise possessed of it. This contrariety, while it shews 

 the difficulty of the subject, may be in some measure explained by 

 the indefiniteness of tastes when faintly perceived by small portions 

 of the surface, by the influence on taste of the commonly associated 

 senses of touch and smell, by some diversities really existing in 

 different individuals, and by the ambiguity necessarily attending 

 experiments on special sensation among the lower animals. As 

 the subject is interesting in its bearing on the question of the 

 nerves of taste, we shall here briefly consider it. 



Touch, as it exists in the tongue and other highly endowed parts, 

 discovers to us not merely the presence and physical properties of 

 bodies, but their actual position : we recognize the situation of the 

 impression in reference to the whole organ, by virtue of a power 

 common in a greater or less degree to all sensitive nerves (p. 403). 

 Every one who has attended to the effect of sapid substances 

 applied to small separate parts of the tongue must feel that a simi- 

 lar capacity of assigning the position of flavours accompanies the 

 sensation of taste ; and on this power in the nerves of taste, aided, 

 as is usually the case, by the nerves of touch, we greatly rely for 

 the determination of the question before us. 



In the first place, all allow that acute taste resides at the base of 

 the tongue, over a region, of which the circumvallate papillae may 

 be taken as the centre, and also on the sides near the base. These 

 parts are supplied solely by the glossal twigs of the glosso-pha- 

 ryngeal nerves. 



Secondly, some writers, among whom are Valentin and Wagner, 

 believe the middle and anterior parts of the dorsum of the tongue to 

 be usually incapable of appreciating flavours; while numerous others 

 hold the contrary opinion, with which our own careful and repeated 

 experiments, on other persons as well as ourselves, quite accord. 

 Sour, sweet, and bitter substances applied to the sides, and espe- 

 cially to the tip, of the protruded tongue, we find to be at once 



